Zacharias Dase

Johann Martin Zacharias Dase was a German mental calculator, born in Hamburg on 23 June 1824 and dead there on 11 September 1861. He left school with little sense that it had shaped him, spent much of his boyhood playing dominoes, which he credited with building his calculating skill, and lived with epilepsy from early childhood. From the age of fifteen he toured Germany, Austria and England giving public exhibitions. He multiplied 79532853 by 93758479 in 54 seconds, two 100-digit numbers in 8 hours 45 minutes, and in 1844 worked out pi to 200 decimal places in about two months from a Machin-like arctangent formula. He also computed a seven-digit logarithm table and extended a table of integer factorizations from 6,000,000 to 9,000,000. He had very little feeling for mathematical theory, yet Carl Friedrich Gauss admired his skill and urged the Hamburg Academy of Sciences to employ him full time, though Dase died soon after.